Collision type identifying device

ABSTRACT

A collision type identifying device is disposed in a central portion of a vehicle main body and has first deceleration detecting means ( 22 ), peak time detecting means ( 32 ), required time detecting means ( 34 ), and type identifying means ( 36 ). The deceleration detecting means ( 22 ) detects a vehicle deceleration in the longitudinal direction. The peak time detecting means ( 32 ) detects, as a first peak time (tp), a time from the excess of a preset threshold (GTH) by a waveform of the vehicle deceleration (G) detected by the deceleration detecting means ( 22 ) to a first peak. The required time detecting means ( 34 ) detects, as a required time (tn), a time when an integrated deceleration (VG) obtained through time quadrature of the vehicle deceleration (G) becomes equal to a predetermined integrated value set in advance. The type identifying means ( 36; 78 ) identifies a vehicle collision type on the basis of the first peak time (tp) and the required time (tn). The collision type identifying device can identify a vehicle collision as one of a plurality of collision types at once.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention relates to a collision type identifying device usedin activating a passenger protection system of a vehicle.

[0003] 2. Description of the Related Art

[0004] According to the related art, a passenger protection system suchas an air bag system installed in a vehicle is designed such that thetiming for activation, the deployment output of an inflator, or the likeis adjusted on the basis of time-based changes in the decelerationdetected by a deceleration meter or the like disposed in the vehicle.

[0005] It is to be noted, however, that there are various vehiclecollision types as shown in FIGS. 1A to 1D. In the case of a head-oncollision (A), the front face of a vehicle 1 collides against an object2. In the case of an oblique collision (B), the vehicle 1 collidesagainst an object 3 at a certain angle. In the case of a pole collision(C), the front center of the vehicle 1 collides against a telegraph pole4 or the like. In the case of an offset collision (D), one side of thefront face of the vehicle 1 collides against an object 5.

[0006] While the head-on collision (A) and the pole collision (C) areclassified into a laterally symmetrical collision type, the obliquecollision (B) and the offset collision (D) are classified into alaterally asymmetrical collision type. The direction, amount, timing, orthe like of displacement of passengers in the event of a vehiclecollision differs depending on whether the collision is symmetrical orasymmetrical. Furthermore, the offset collision (D) is classified intoORB (Offset Rigid Barrier) and ODB (Offset Deformable Barrier). In thecase of ORB, the vehicle 1 collides against a rigid object. In the caseof ODB, the vehicle 1 collides against a deformable object. Thedirection, amount, timing, or the like of displacement of passengersalso differs depending on whether the offset collision (D) is ORB orODB.

[0007] Accordingly, there is a limit to the aptness in driving thepassenger protection system simply on the basis of time-baseddeceleration changes occurring in the vehicle. That is, althoughreliable detection of a vehicle collision type leads to the driving ofthe passenger protection system at a suitable timing and thus to theprotection of passengers, it is difficult to detect a collision typeprecisely.

[0008] To overcome the difficulty, the present applicant proposesdevices for identifying a vehicle collision type. In one of them(Japanese Patent Application Laid-Open 2001-30873), deceleration sensors(satellite sensors) are disposed at a plurality of locations in avehicle in addition to a deceleration sensor (floor sensor) disposed onthe center side of a main body of the vehicle. A collision type isidentified on the basis of decelerations detected by these sensors andis utilized to control the timing suited to ignite an air bag system oran output state of the air bag. Thus, passengers are protected reliably.If a vehicle is equipped with the device thus constructed, passengerscan be protected in accordance with the vehicle collision type and thusmore reliably in comparison with the former case.

[0009] However, the vehicle deceleration at which the passengerprotection system is to be activated in the event of an obliquecollision or an ODB collision is often close to the vehicle decelerationat which the passenger protection system is not to be activated in theevent of an ORB collision. Similarly, the vehicle deceleration at whichthe passenger protection system is to be activated in the event of apole collision is often close to the vehicle deceleration at which thepassenger protection system is not to be activated in the event of ahead-on collision. In many cases, it is still difficult to identify avehicle collision type with high precision simply on the basis of avehicle deceleration.

[0010] As shown in FIGS. 1A to 1D, vehicle collision types areclassified into symmetrical collision types and asymmetrical collisiontypes. Furthermore, the vehicle may collide against objects withdifferent rigidities. Thus, more precise identification of a collisiontype inevitably requires a plurality of identification processings.

SUMMARY OF THE INVENTION

[0011] The invention has been made in view of the aforementionedcircumstances. It is an object of the invention to provide a collisiontype identifying device capable of identifying a vehicle collision typeas one of a plurality of collision types at once.

[0012] The aforementioned object is achieved by providing a collisiontype identifying device disposed in a central portion of a vehicle mainbody and comprising first deceleration detecting means for detecting avehicle deceleration in the longitudinal direction, peak time detectingmeans for detecting, as a first peak time tp, a time from the excess ofa preset threshold GTH by a waveform of the vehicle decelerationdetected by the deceleration detecting means to a first peak, requiredtime detecting means for detecting, as a required time tn, a time whenan integrated deceleration obtained through time quadrature of thevehicle deceleration becomes equal to a predetermined integrated value,and type identifying means for identifying a vehicle collision type onthe basis of the first peak time tp and the required time tn.

[0013] The aforementioned collision type identifying device can identifya vehicle collision type as one of the aforementioned various collisiontypes at once by using the first peak tp and the required time tn, whichare calculated in respect of the waveform of the vehicle decelerationthat is detected periodically.

[0014] Further, the vehicle collision type can be identified on thebasis of the single vehicle deceleration detected by the firstdeceleration detecting means disposed in the central portion of thevehicle main body. Thus, the overall structure can be simplified.

[0015] If the vehicle deceleration is not on a level indicating acollision of the vehicle, it is excluded from consideration by providingthe threshold GTH. The emersion of the first peak in the vehicledeceleration waveform is confirmed on this premise. Therefore, thecollision type can be identified in the early stages, namely, in aninitial collision phase of the vehicle.

[0016] According to a further aspect of the invention, the predeterminedintegrated value may be set in advance as a predetermined integrateddeceleration corresponding to a required time, which is a critical valuefor determining whether to activate a passenger protection system in theevent of a collision of the vehicle.

[0017] According to a further aspect of the invention, the required timedetecting means may have a function of calculating an integrateddeceleration through time quadrature of the vehicle deceleration and maybe so set as to start calculating the integrated deceleration uponexcess of the threshold by the vehicle deceleration and to detect arequired time when the integrated deceleration becomes equal to therequired integrated value.

[0018] In identifying the collision type, the collision type identifyingdevice thus constructed uses the required integrated value that reflectsthe vehicle collision state accurately. Thus, the collision type can beidentified reliably.

[0019] According to a further aspect of the invention, the peak timedetecting means may confirm the first peak on the basis of an event inwhich a Wavelet phase obtained by subjecting the waveform of the vehicledeceleration to a Wavelet transformation processing is first invertedfrom 2π to 0 in the case where it is defined in the range 2π to 0, andmay detect the first peak time tp.

[0020] Because the collision type identifying device thus constructeduses the Wavelet transformation processing, it is possible to confirmthe emersion of the first peak in the vehicle deceleration and detectthe first peak time tp with high precision. Thus, the collision type canbe identified with enhanced precision.

[0021] According to a further aspect of the invention, the typeidentifying means may have a collision type identifying map which isformed of the first peak time tp and the required time tn and on which aplurality of identification areas are set, and may identify a vehiclecollision type by confirming to which one of the identification areas aspecific point determined at the time of detection of the first peaktime tp and the required time tn belongs.

[0022] The collision type identifying device thus constructed canidentify a collision type easily by confirming to which one of theidentification areas on the collision type identifying map the specificpoint determined at the time of detection of the first peak time tp andthe required time tn belongs.

[0023] According to a further aspect of the invention, it is preferablethat the predetermined integrated value be 0.7 to 0.8 m/s.

[0024] The collision type identifying device thus constructed canidentify a collision type with higher precision. For example, it ispreferable that the integrated deceleration corresponding to therequired time in the event of a high-speed head-on collision of thevehicle be the standard for the predetermined integrated value. If thisintegrated deceleration is set as a reference for the predeterminedintegrated value, various collision types can be identified precisely bymeans of the required time tn and the first peak tp. The aforementionedpredetermined integrated value is set according to the vehicle type andis e.g. about 0.7 to 0.8 m/s.

[0025] According to another aspect of the invention, the aforementionedobject is also achieved by a collision type identifying device disposedin a central portion of a vehicle main body and comprising firstdeceleration detecting means for detecting a vehicle deceleration in thelongitudinal direction, second deceleration detecting means that aredisposed in front of and to the left and right of the first decelerationdetecting means and that detect vehicle decelerations in thelongitudinal direction of the vehicle as left-side and right-sidedecelerations, peak time detecting means for detecting, as a first peaktime tp, a time from the excess of a preset threshold GTH by a waveformof the vehicle deceleration G detected by the deceleration detectingmeans to a first peak, required time detecting means for detecting, as arequired time tn, a time when an integrated deceleration VG obtainedthrough time quadrature of the vehicle deceleration G becomes equal to apredetermined integrated value, time ratio calculating means forcalculating a time ratio tn/tp between the first peak time tp and therequired time tn, symmetrical index detecting means for detecting alateral symmetrical index in the event of a collision of the vehicle onthe basis of the left-side deceleration and the right-side deceleration,and type identifying means for identifying a vehicle collision type onthe basis of the time ratio and the lateral symmetrical index.

[0026] The collision type identifying device thus constructed uses thetime ratio as a guideline for an absorption state of an impact causedbetween the vehicle and an object and the lateral symmetrical indexdetected by the second deceleration detecting means. Thus, the collisiontype can be identified with higher precision.

[0027] According to a further aspect of the invention, the predeterminedintegrated value may be set in advance as a predetermined integrateddeceleration corresponding to a required time, which is a critical valuefor determining whether to activate a passenger protection system in theevent of a collision of the vehicle.

[0028] According to a further aspect of the invention, the required timedetecting means may have a function of calculating an integrateddeceleration through time quadrature of the vehicle deceleration and maybe so set as to start calculating the integrated deceleration upon theexcess of the threshold GTH by the vehicle deceleration and to detect arequired time tn when the integrated deceleration becomes equal to thepredetermined integrated value.

[0029] In identifying the collision type, the collision type identifyingdevice thus constructed uses the predetermined integrated value thatreflects the vehicle collision state accurately. Thus, the collisionstate can be identified more reliably.

[0030] According to a further aspect of the invention, it is preferablethat the symmetrical index detecting means have a function ofcalculating a left-side integrated deceleration and a right-sideintegrated deceleration through time quadrature of the left-sidedeceleration and the right-side deceleration respectively and detect alateral symmetrical index in the event of a collision of the vehicle onthe basis of the left-side integrated deceleration and the right-sideintegrated deceleration.

[0031] Because the collision type identifying device thus constructeduses the left-side integrated deceleration and the right-side integrateddeceleration, the lateral symmetrical index can be detected with thenoise effect reduced in comparison with the case where the left-sidedeceleration and the right-side deceleration are used directly.

[0032] According to a further aspect of the invention, the symmetricalindex detecting means may detect the lateral symmetrical index on thebasis of a lateral ratio between the left-side integrated decelerationand the right-side integrated deceleration, which are obtained throughintegration for a predetermined time set in advance after the first peaktime tp or the threshold GTH has been exceeded.

[0033] According to a further aspect of the invention, if the left-sideintegrated deceleration and the right-side integrated deceleration areobtained in respect of the first peak time tp, the lateral symmetricalindex can be detected with high precision. The predetermined timeensuring reliable detection of the lateral symmetrical index may be setin advance. However, it is desirable in this case that the predeterminedtime be so set as to allow detection of the lateral symmetrical indexbefore calculation of the aforementioned time ratio.

[0034] According to a further aspect of the invention, the peak timedetecting means may confirm the first peak on the basis of an event inwhich a Wavelet phase obtained by subjecting the waveform of the vehicledeceleration to a Wavelet transformation processing is first invertedfrom 2π to 0, and may detect the first peak time tp.

[0035] Because the collision type identifying device thus constructeduses the Wavelet transformation processing, it is possible to confirmthe emersion of the first peak in the vehicle deceleration and detectthe first peak time tp with high precision. Therefore, the collisiontype can be identified with further enhanced precision.

[0036] According to a further aspect of the invention, the typeidentifying means may have a collision type identifying map which isformed of the time ratio and the lateral symmetrical index and on whicha plurality of identification areas are set, and may identify a vehiclecollision type by confirming to which one of the identification areas aspecific point determined at the time of detection of the time ratio andthe lateral symmetrical index belongs.

[0037] The collision type identifying device thus constructed canidentify a vehicle collision type as one of a plurality of collisiontypes easily by confirming to which one of the identification areas onthe collision type identifying map the specific point determined as aresult of detection of the time ratio and the lateral symmetrical indexbelongs.

[0038] According to a further aspect of the invention, it is preferablethat the predetermined integrated value be 0.7 to 0.8 m/s.

[0039] The collision type identifying device thus constructed canidentify a collision type with higher precision.

BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The above and other objects, features, advantages, and technicaland industrial significance of this invention will be better understoodby reading the following detailed description of exemplary embodimentsof the invention, when considered in connection with the accompanyingdrawings, in which:

[0041]FIGS. 1A to 1D show examples of vehicle collision types;

[0042]FIG. 2 shows the hardware structure of a collision typeidentifying device according to a first embodiment of the invention;

[0043]FIG. 3 is an exemplary view showing how the collision typeidentifying device shown in FIG. 2 is installed in a vehicle;

[0044]FIG. 4 is a functional block diagram of the overall structure ofthe collision type identifying device shown in FIG. 2;

[0045]FIG. 5 shows an exemplary floor G waveform that is detected by afloor sensor periodically;

[0046]FIG. 6 shows how a first peak time tp and a required time tn arerelated to each other in respect of data obtained by a vehicle collisiontest;

[0047]FIG. 7 is an explanatory view exemplifying the representation of aGabor function along a time axis;

[0048]FIG. 8 is an explanatory view showing how a real part R, animaginary part I, a magnitude p, and a phase θ of Wavelet transformationX(a, b) are related to one another;

[0049]FIG. 9 is an exemplary view of a type identifying map employed ina type identifying portion according to the first embodiment of theinvention;

[0050]FIG. 10 shows an exemplary identification routine that is executedby the type identifying portion of the collision type identifying deviceaccording to the first embodiment of the invention;

[0051]FIG. 11 shows the hardware structure of a collision typeidentifying device according to a second embodiment of the invention;

[0052]FIG. 12 is an exemplary view showing how the collision typeidentifying device shown in FIG. 11 is installed in the vehicle;

[0053]FIG. 13 is a functional block diagram of the overall structure ofthe collision type identifying device shown in FIG. 11;

[0054]FIG. 14 shows examples of front LG and front RG waveforms togetherwith a front G waveform that is detected by a floor sensor periodically;

[0055]FIG. 15 is an exemplary view of a type identifying map employed ina type identifying portion according to the second embodiment of theinvention; and

[0056]FIG. 16 shows an exemplary identification routine that is executedby the type identifying portion of the collision type identifying deviceaccording to the second embodiment of the invention.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS DESCRIPTION OF THEEXEMPLARY EMBODIMENTS

[0057] In the following description and the accompanying drawings, theinvention will be described in more detail in terms of exemplaryembodiments.

[0058] Two embodiments of the invention will be described hereinafterwith reference to the drawings.

[0059] The first embodiment handles a collision type identifying devicethat identifies a vehicle collision type on the basis of a vehicledeceleration (hereinafter referred to as floor G) obtained from a floorsensor disposed in a floor tunnel or the like in a central portion of avehicle main body.

[0060] The second embodiment handles a collision type identifying devicethat identifies a vehicle type using first and second vehicledecelerations. The first vehicle deceleration is a vehicle deceleration(floor G) obtained from the aforementioned floor sensor. The secondvehicle decelerations are a left-side vehicle deceleration (hereinafterreferred to as front LG) obtained from a front-left sensor that isdisposed on the left side and in front of the floor sensor and aright-side vehicle deceleration (hereinafter referred to as front RG)obtained from a front-right sensor that is disposed on the right sideand in front of the floor sensor.

[0061] The first embodiment and the second embodiment will be describedhereinafter in this order.

[0062] First Embodiment

[0063]FIG. 2 shows the hardware structure of a collision typeidentifying device 20 according to the first embodiment. FIG. 3 is anexemplary view showing how the collision type identifying device 20 isinstalled in a vehicle 10. FIG. 4 is a functional block diagram of theoverall structure of the collision type identifying device 20. It is tobe noted herein that FIG. 2 shows, as an example, an air bag system 50that is driven on the basis of a result obtained from the collision typeidentifying device 20.

[0064] As shown in FIGS. 2 and 3, a main body of the collision typeidentifying device 20 of this embodiment is disposed in a floor tunnelclose to a console in a central portion of the vehicle 10, and includes,as a component thereof, a floor sensor 22 for detecting a floor G in thelongitudinal direction of the vehicle.

[0065] The collision type identifying device 20 includes a microcomputer40 that identifies a collision type of the vehicle 10 on the basis of awaveform of the floor G that is detected by the floor sensor 22periodically. The microcomputer 40 is constructed mainly of a CPU 42 andincludes a ROM 44 for storing predetermined processing programs, a RAM46 for temporarily storing data, an I/O circuit 48, and the like.

[0066] The CPU 42 is so set as to monitor the floor G constantly andcontinuously at intervals of a predetermined period (e.g. 2 KHz) after astarting timing, which follows the turn-on of an ignition (IG) switch ofthe vehicle, depression of an accelerator pedal, or the like.Furthermore, the CPU 42 realizes a collision type identifying portion30. If the vehicle 10 collides, the collision type identifying portion30 identifies the collision type as head-on collision, obliquecollision, ORB, ODB, or pole collision, using the floor G. Thefunctional block diagram of the collision type identifying device 20shown in FIG. 4 clarifies the structure of the CPU 42.

[0067] In FIG. 4, the floor G that is detected by the floor sensor 22periodically is supplied to the collision type identifying portion 30via a signal input portion 28. The collision type identifying portion 30includes a peak time detecting portion 32, a required time detectingportion 34, and a type identifying portion 36. The peak time detectingportion 32 confirms the emersion of a first peak in the decelerationwaveform of the floor G and detects a first peak time tp. The requiredtime detecting portion 34 detects, as a required time tn, a time when anintegrated deceleration VG obtained by time quadrature (or called timeintegration) of the floor G becomes equal to a required integrated valueset in advance.

[0068] The peak time detecting portion 32 confirms the emersion of thefirst peak in the floor G waveform with the aid of the Wavelettransformation processing, and detects a time of the emersion as a firstpeak time tp. In this embodiment, the first peak time tp is defined as atime from the excess of a predetermined threshold GTH by the floor G tothe emersion of the first peak.

[0069] If the first peak emerges in the aforementioned floor G waveform,it is almost certain that the vehicle has collided. In identifying thevehicle collision type, it is effective to confirm the first peak andidentify the collision type on the basis of the first peak. If the peaktime detecting portion 32 detects the first peak time tp, a detectionsignal output from the peak time detecting portion 32 is supplied to thetype identifying portion 36.

[0070] If the vehicle deceleration is not on a level indicating avehicle collision, it is excluded from consideration by providing thethreshold GTH. The emersion of the first peak in the vehicledeceleration waveform is confirmed on this premise. Therefore, thecollision type can be determined in the early stages, namely, in aninitial collision phase of the vehicle.

[0071]FIG. 5 shows an exemplary floor G waveform that is detected by thefloor sensor 22 periodically. The upper stage of FIG. 5 shows thewaveform of the floor G, and the lower stage of FIG. 5 shows a Waveletphase obtained by subjecting the waveform of the floor G to Wavelettransformation.

[0072] Referring to the upper stage of FIG. 5, the peak time detectingportion 32 detects the first peak time tp in response to the emersion ofthe first peak, under the assumption that the floor G exceeds thepredetermined threshold GTH at a reference time t0 (=0). It is to benoted in this embodiment that the floor G exceeds the threshold GTH atthe time t0 and that the first peak emerges at the time tp. However,since t0=0, it follows that the first peak time=(tp−0). Therefore, thefirst peak time is described as tp. The Wavelet phase in the lower stageof FIG. 5 is used to detect the aforementioned first peak. This Waveletprocessing will be described later in detail.

[0073] The required time detecting portion 34 detects, as the requiredtime tn, a time when the integrated deceleration VG (∫Gdt) obtained bytime quadrature of the floor G becomes equal to the required integratedvalue set in advance. This required integrated value is set in advanceas the predetermined integrated deceleration VG corresponding to arequired time, which is a critical value for determining whether toactivate a passenger protection system in the event of a vehiclecollision.

[0074] The required time detecting portion 34 has a function ofprocessing the floor G through integration. As in the case of the peaktime detecting portion 32, the required time detecting portion 34calculates the integrated deceleration VG continuously after the floor Ghas exceeded the threshold GTH (the time when the floor G exceeds thethreshold GTH is the reference time to). The required time detectingportion 34 detects, as the required time tn, a time when the integrateddeceleration VG becomes equal to the aforementioned required integratedvalue.

[0075] The aforementioned required integrated value will now bedescribed. There is a critical time for determining whether to activatea passenger protection system such as an air bag in the event of acollision of the vehicle. In order to protect passengers suitably in theevent of a vehicle collision, it must be determined before the criticaltime whether to activate the passenger protection system. In the presentspecification, the critical time for this determination is referred toas the required time. As well as the aforementioned first peak, thisrequired time reflects a state in the event of a vehicle collision.Therefore, it is effective to identify the collision type on the basisof the required time.

[0076] That is, the aforementioned required time tends to be short inthe case of a high-speed head-on collision or the like, and tends to berelatively long in the case of a pole collision. The required time forother collision types such as ORB, ODB, and oblique collision tends tobe between the required time for head-on collision and the required timefor pole collision. Furthermore, the required time differs among thesecollision types. Since ORB means a collision against a rigid object, therequired time for ORB tends to be close to the required time for head-oncollision. Since ODB means a collision against a deformable object, therequired time for ODB tends to be close to the required time for polecollision. That is, although there are a plurality of collision types onwhich the floor G waveform depends, the required time serves as aguideline for identifying the collision type.

[0077] If attention is paid to the integrated deceleration VG obtainedby time quadrature of the floor G in the upper stage of FIG. 5 from thestandpoint as mentioned above, the integrated deceleration VG isrepresented as an area below the floor G waveform. In the case of ahead-on collision, this area is large in its initial stage. On thecontrary, in the case of a pole collision, this area is large in itslater stage. This embodiment is based on a result of studies that thevehicle collision type is identified effectively by using a time(required time) when the area becomes equal to the predeterminedintegrated deceleration VG corresponding to the required timeconstituting the critical time for determining whether to activate thepassenger protection system.

[0078] For example, the integrated deceleration VG at the required timein the event of a high-speed head-on collision is defined as a requiredintegrated value and used as a criterion in advance. The time when theintegrated deceleration VG of the floor G detected periodically from thevehicle that has collided becomes equal to the required integratedvalue, namely, the required time tn is used to identify the collisiontype. This required integrated value, which is constant, is reachedearly in the case of a head-on collision and latest in the case of apole collision. In the case of an ORB, ODB, or oblique collision, ittakes an intermediate period to reach the required integrated value.

[0079] The aforementioned required integrated value is obtained, forexample, by conducting a test based on a high-speed head-on collisionand calculating the integrated deceleration VG corresponding to therequired time. The integrated deceleration VG is set in advance as therequired integrated value of the vehicle. It is preferable that therequired integrated value be set by conducting a collision test and asimulation according to the vehicle type. For example, the requiredintegrated value is 0.7 to 0.8 m/s. In this embodiment, the requiredintegrated value=0.75 m/s.

[0080] The required time tn detected by the required time detectingportion 34 is supplied to the type identifying portion 36 as a detectionsignal.

[0081] The type identifying portion 30 uses the required time tn and thefirst peak time tp obtained from the peak time detecting portion 32 andidentifies a vehicle collision as head-on collision, oblique collision,ORB, ODB, or pole collision.

[0082] Furthermore, a method that is adopted by the type identifyingportion 36 in the first embodiment so as to identify a vehicle collisionas one of a plurality of collision types will be described.

[0083]FIG. 6 shows how the first peak time tp and the required time tnare related to each other in respect of data obtained by a vehiclecollision test. The axis of abscissa represents the required time tn,and the axis of ordinate represents the first peak time tp. In thiscollision test, the required integrated value is 0.75 m/s. That is, therequired time tn is a time when time quadrature of the floor G (m/s²)results in 0.75 m/s.

[0084] In FIG. 6, while data regarding head-on collisions tend to gatherin the upper-left region, data regarding pole collisions tend to gatherin the lower-right region. Data regarding the other collisions arelocated between the data regarding head-on collisions and the dataregarding pole collisions. The first peak time tp for ODB is shorterthan the first peak time tp for oblique collisions, which is in turnshorter than the first peak time tp for ORB.

[0085] As regards the first peak time tp, the first peak time requiredby the data regarding head-on collision or ORB is longer than the firstpeak time required by the data regarding oblique collisions or ODB. Thisis because the first peak time tp is measured immediately after thethreshold GTH has been exceeded. That is, in the case of a head-on orORB collision, the floor G waveform exceeds the threshold GTH in theinitial stage of the collision and then reaches the first peak. However,in the case of an oblique or ORB collision, the floor G waveform doesnot exceed the threshold GTH immediately in the initial stage of thecollision but tends to exceed the threshold GTH in the intermediate tolate stage of the collision and to reach the first peak thereafter allof a sudden. Accordingly, the axis of ordinate in FIG. 6 demonstratesthat the first peak time tp for head-on or ORB collisions is relativelylong.

[0086] As is apparent from FIG. 6, it is understandable that a vehiclecollision can be identified at once as one of a plurality of collisiontypes if a relation between the required time tn and the first peak timetp of the floor G waveform is used.

[0087] The floor sensor 22 is disposed at the center of the vehicle mainbody and thus detects the floor G stably until a breakage spreading tothe vehicle center side is caused. However, according to the relatedart, the possibilities of employing other sensors accessorily have beenconsidered on the ground that the floor G alone does not allow a certaincollision to be identified as one of a plurality of collision types.However, this embodiment allows a certain collision to be identified asone of a plurality of collision types at once by using the required timetn and the first peak time tp of the floor G waveform.

[0088] A method in which the peak time detecting portion 32 detects thefirst peak time of the floor G waveform will now be described withreference to FIGS. 7 and 8.

[0089] In this embodiment, the peak time detecting portion 32 subjectsthe waveform of the floor G supplied via the signal input portion 28 tothe Wavelet transformation processing, confirms the emersion of thefirst peak (first maximum value) of the floor G waveform, and detectsthe first peak time tp.

[0090] While Fourier transformation represents a time series signal as asuperposition of constant sinusoidal waves, Wavelet transformation is amethod of representing a time series signal as a superposition oftemporally localized waves (wavelets). Wavelet transformation is a dataconversion method that has recently been applied widely to variousfields including the spectral analysis of non-constant signals, speechrecognition/synthesis, the compression of image information, noiseremoval, and the detection of malfunctions.

[0091] The peak time detecting portion 32 performs a product-sumoperation by using a predetermined complex function as an integrationbase for an input signal, and calculates a phase θ of the magnitude of aWavelet transformation value on the basis of a real part P and animaginary part I thereof. A time corresponding to the first maximumvalue is detected on the basis of the phase θ thus calculated.Hereinafter, a principle by which the peak time detecting portion 32detects the first peak by means of the Wavelet transformation methodwill be described briefly.

[0092] A Wavelet transformation coefficient (a, b) of a time seriessignal X(t) is developed as exemplified in an equation (2), which has apair of similar functions ψa, b(t) as base functions. The pair of thesimilar functions ψa, b(t) is obtained by preparing a base Waveletfunction ψ(t) that is localized both temporally and frequency-wise,subjecting it to “a”-time scale transformation as indicated by anequation (1), and then subjecting it to shift transformation(translation) by an origin “b”. It is to be noted herein that a scaletransformation parameter “a” is inversely proportional to atransformation frequency “f”.

ψb(t)=a− ^(1/2)ψ((t−b)/a)  (1)

X(a,b)=∫X(t)ψa,b(t)  (2)

[0093] In this embodiment, a Gabor function expressed by an equation (3)is used as the base Wavelet function ψ(t). The Gabor function is acomplex function in which the imaginary part I is different in phase byπ/2 from the real part R. It is to be noted herein that Ω₀ in theequation (3) is a constant determined by the frequency “f” (ω₀=2πf) andthat α is a constant as well. $\begin{matrix}\begin{matrix}{{\psi (t)} = {\exp \left( {{{- \alpha}\quad t^{2}} + {\quad \omega_{0}t}} \right)}} \\{= {\left\{ {\exp \left( {{- \alpha}\quad t^{2}} \right)} \right\} \times \left\{ {{\cos \left( {\omega_{0}t} \right)} + {\quad {\sin \left( {\omega_{0}t} \right)}}} \right\}}}\end{matrix} & (3)\end{matrix}$

[0094]FIG. 7 shows the representation of the Gabor function along a timeaxis in the case where α=π in the equation (3). As shown in FIG. 7, theGabor function is localized in a range of −T to T along the time axis,and the real part waveform and the imaginary part waveform are differentin phase by π/2. More concretely, Wavelet transformation for the timeseries signal X(t) is a product-sum operation of the time series signalX(t) and a function having the suitably selected scale transformationparameter “a” (w₀ in the equation (3)). The operation section isconfined to a range with localized waveforms (in the range of −T to T inFIG. 7). This range is referred to as a window.

[0095] Because the Gabor function is a complex function, Wavelettransformation X(a, b) of the time series signal X(t) based on the Gaborfunction is represented as a complex number. FIG. 8 shows a relationamong the real part R, the imaginary part I, the magnitude P, and thephase θ of Wavelet transformation X(a, b). The magnitude P is calculatedaccording to an equation (4), and the phase θ is obtained from anequation (5). It is to be noted herein that the magnitude P means alogical magnitude of Wavelet transformation X(a, b) and is adimensionless quantity. The phase θ changes within the range of 0 to 2πdepending on the magnitudes and signs of the real part R and theimaginary part I.

P=(R ² +I ²)^(1/2)  (4)

θ=tan−¹(I/R)  (5)

[0096] The phase θ(t) of the transformation frequency “f” close to thefrequency of the time series signal X(t) changes from 2π to 0 when thetime series signal X(t) has a maximum (peak) amplitude. The phase θ(t)becomes equal to π when the time series signal X(t) has a minimum(bottom) amplitude.

[0097] The peak time detecting portion 32 of this embodiment detects atime tp corresponding to the first emersion of the first peak (firstmaximum value). If one further waits until a time tb corresponding tothe first emersion of the first bottom (first minimum value) isdetected, the emersion of the first peak can be confirmed more reliably.

[0098] That is, if it is confirmed that the phase θ first exceeds π andthen drops below π, it is concluded that the phase θ has shifted from 2πto 0. Thus, the time tp corresponding to the first peak is detectedindirectly. The first bottom emerges at a time when the phase θ becomesequal to π subsequently.

[0099] The aforementioned lower stage of FIG. 5 shows a Wavelet phasewaveform, which is obtained by subjecting the floor G waveform detectedby the floor G sensor 22 as shown in the upper stage of FIG. 5 to theWavelet transformation processing. By using the Wavelet transformationmethod as described above, the first peak is detected at the time tpwhen the phase θ is inverted from 2 π to 0. The first bottom emerges atthe time tb when the phase θ exceeds π.

[0100] Referring again to FIG. 4, as described above, the peak detectingportion 32 detects the first peak time tp of the floor G waveform andsupplies it to the type identifying portion 36, and the required timedetecting portion 34 detects the required time tn and supplies it to thetype identifying portion 36. The type identifying portion 36 identifiesa collision type by means of a type identifying map shown in FIG. 9. Asshown in FIG. 9, identification areas for prediction of respectivecollision types are set in this type identifying map. A collision typecan be identified easily by confirming to which one of theidentification areas a point that is determined specifically upondetection of the first peak time tp and the required time tn belongs. Itis to be noted in this embodiment that the required integrated value is0.75 m/s and that the required time tn is represented as t0.75 in FIG.9. In consideration of the aforementioned relation shown in FIG. 6, thetype identifying map shown in FIG. 9 is set suitably by referring tocollision data or the like according to the vehicle type. This typeidentifying map is stored in advance in the ROM 44 or the like in themicrocomputer 40.

[0101]FIG. 10 shows an exemplary identification routine that is executedby the type identifying portion 36, which is realized by the CPU 42 ofthe collision type identifying device 20.

[0102] Referring to FIG. 10, if one of the first peak time tp and therequired time tn is detected, the type identifying portion 36 preparesfor the identification of a collision type (S100). Furthermore, if theremaining one of the first peak time tp and the required time tn isdetected (S102), the type identification processing is performed bymeans of the type identifying map.

[0103] A specific point determined by the detected first peak time tpand the required time tn is then located on the type identifying map instep S104. It is then confirmed to which one of the identification areasset in advance according to the collision type this specific pointbelongs, and the collision type is identified (S106). The processings ofthe present routine are then terminated.

[0104] A result obtained from the type identification based on thepresent routine is used to perform activation control of the passengerprotection system 50 shown in FIG. 2. The air bag system 50 shown inFIG. 2 will now be described briefly. The air bag system 50 includes anair bag 52, two inflators 54, 54 for supplying gas to the air bag 52,ignition devices 56, 56 for igniting a gas generator (not shown), anddrive circuits 58, 58 for energizing and igniting the ignition devices56, 56 on the basis of an activation signal output from themicrocomputer 40. The two inflators 54 are provided because two casesare taken into account. In one of the cases, that is, in the case ofhigh output, the two inflators 54 are operated simultaneously so as todeploy the air bag 52 at a high speed. In the other case, that is, inthe case of low output, the two inflators 54 are operated with a timedifference. Depending on the vehicle collision type, it is determinedwhether to select high output or low output.

[0105] As described above, the collision type identifying device 20 ofthe first embodiment can identify a collision of the vehicle 10 as oneof a plurality of collision types at once by using the required time tnand the first peak time tp of the floor G waveform detected by the peaktime detecting portion 32. In particular, it has been believed accordingto the related art that the identification of a vehicle collision typefrom the floor G is difficult. However, this embodiment makes itpossible to identify from the floor G the type of a collision in whichthe vehicle is involved. If the collision type identifying device 20constructed as described above is applied to a passenger protectionsystem such as an air bag system, passengers can be protected reliably.

[0106] Second Embodiment

[0107] Furthermore, the second embodiment of the invention will bedescribed with reference to FIGS. 11 to 16. FIG. 11 shows the hardwarestructure of a collision type identifying device 60 according to thesecond embodiment of the invention. FIG. 12 is an exemplary view showinghow the collision type identifying device 60 is installed in thevehicle. FIG. 13 is a functional block diagram of the overall structureof the collision type identifying device 60. These drawings arerespectively similar to FIGS. 2 to 4, which show the first embodiment ofthe invention.

[0108] The second embodiment handles the collision type identifyingdevice 60 that identifies a vehicle collision type using second vehicledecelerations in addition to the floor G detected by the floor sensor22. The second vehicle decelerations are a left-side vehicledeceleration (front LG) detected in front of and to the left of thefloor G and a right-side vehicle deceleration (front RG) detected infront of and to the right of the floor G.

[0109] It is to be noted herein that the same components as in thestructure of the aforementioned first embodiment are denoted by the samereference numerals and that the following description will be focused onthe characteristic part of the second embodiment.

[0110] The collision type identifying device 60 of the second embodimentis also disposed close to the console in the central portion of thevehicle 10. In addition to the floor sensor 22 for detecting the vehicledeceleration floor G in the longitudinal direction of the vehicle 10, afront-left sensor 24 for detecting a deceleration front LG in thelongitudinal direction of the vehicle and a front-right sensor 26 fordetecting a deceleration front RG in the longitudinal direction of thevehicle are provided. The front-left sensor 24 and the front-rightsensor 26 are installed in front of left and right side members (in acrash zone) respectively. That is, the microcomputer 40 of thisembodiment identifies a collision type using the front LG and the frontRG in addition to the floor G.

[0111] In the second embodiment, deceleration signals output from thefront-left and front-right sensors 24, 26 are input to the side of themicrocomputer 40 via wires 25, 27 respectively. Accordingly, raw dataregarding decelerations detected on the sides of the front-left andfront-right sensors 24, 26 and raw data regarding the vehicledecelerations on the side of the floor sensor 22 are processedcomprehensively on the side of the microcomputer 40. The comprehensiveprocessing on the side of the microcomputer 40 as mentioned herein ispreferred because data can be processed with higher quality incomparison with cases where data processed in advance on the sides ofthe front-left and front-right sensors 24, 26 are transmitted.

[0112] The CPU 42 is so set as to monitor the front LG and the front RGas well as the floor G detected by the floor sensor 22. The CPU 42realizes a collision type identifying portion 70 that identifies acertain collision as head-on collision, oblique collision, ORB, ODB, orpole collision by means of three vehicle decelerations detected by thefloor sensor 22 and the front-left and front-right sensors 24, 26,namely, the floor G, the front LG, and the front RG. The functionalblock diagram of the collision type identifying device 60 shown in FIG.13 clarifies the structure of the CPU 42.

[0113] Referring to FIG. 13, the floor G, the front LG, and the frontRG, which are detected periodically, are supplied to the collision typeidentifying portion 70 via the signal input portion 28. The collisiontype identifying portion 70 includes the peak time detecting portion 32and the required time detecting portion 34. The peak time detectingportion 32 detects the first peak time tp in the floor G waveform. Therequired time detecting portion 34 detects, as the required time tn, atime when the integrated deceleration VG obtained by time quadrature ofthe floor G becomes equal to a required integrated value.

[0114] In the collision type identifying device 70 shown in FIG. 13 aswell, the basic processing of the waveform of the floor G detected bythe floor sensor 22 is the same as in the case of the first embodiment.The peak time detecting portion 32 and the required time detectingportion 34 detect the first peak time tp and the required time tnrespectively.

[0115] In this embodiment, the first peak time tp and the required timetn are supplied to a time ratio calculating portion 76, which calculatesa time ratio (tn/tp). The time ratio (tn/tp) thus calculated is used foridentification by a type identifying portion 78. The time ratio (tn/tp)can be regarded as a guideline indicating a collision state in whichdeformation occurs to the extent of absorbing an impact caused in theevent of a collision of the vehicle 10.

[0116] That is, impact-absorbing deformation does not occur in the casewhere the vehicle 10 collides against a rigid object, namely, in thecase of a head-on or ORB collision. In this case, the difference betweenthe first peak time tp and the required time tn is small, as a result,the time ratio (tn/tp) is small. On the contrary, in the case of a polecollision, the center of the vehicle front portion is deformed whileabsorbing an impact until the collision extends to a rigid member suchas an engine. Further, in the case of an ODB collision, a collisionobject is deformed. As a result, the required time tn is larger and thetime ratio (tn/tp) is larger in comparison with the case of the head-oncollision or the like. Accordingly, it is effective to use theaforementioned time ratio (tn/tp) as a guideline for identifying acollision type.

[0117] Furthermore, the collision type identifying portion 70 of thisembodiment has a lateral symmetrical index detecting portion 72 as aprocessing portion that calculates a lateral symmetrical index SY of acollision by means of the front LG and the front RG.

[0118]FIG. 14 corresponds to FIG. 5 showing the first embodiment. FIG.14 shows exemplary waveforms of the front LG and the front RG as well asthe waveform of the floor G that is detected by the floor sensor 22periodically. The uppermost stage (first stage) of FIG. 14 shows thefront LG waveform. The second stage of FIG. 14 shows the front RGwaveform. As in the case of FIG. 5, the two lower stages of FIG. 14 showthe floor G waveform and a Wavelet phase obtained by subjecting thefloor G waveform to Wavelet transformation.

[0119] In this embodiment, attention is paid to the fact that the ratiobetween a left-side integrated deceleration LV of the front LG (firststage) and a right-side integrated deceleration RV of the front RG(second stage) reflects the lateral symmetrical index of a collisionaccurately as shown in FIG. 14. This embodiment adds this fact as arequisite for identifying a collision type. It is to be noted hereinthat these integrated values are used to suppress the noise effect.

[0120] For example, as shown in FIG. 14, the left-side integrateddeceleration LV of the front LG is much larger than the right-sideintegrated deceleration RV of the front RG. This makes it possible topredict that an asymmetric collision has occurred and that the vehiclehas collided on its left side.

[0121] The lateral symmetrical index detecting portion 72 integrates thefront LG and the front RG from a time corresponding to the excess of theaforementioned predetermined threshold GTH by the floor G to a timecorresponding to the detection of the first peak of the floor Gwaveform, that is, to the first peak time tp, or integrates the front LGand the front RG for a predetermined time set in advance from the timecorresponding to the excess of the threshold GTH by the floor G. Thus,the lateral symmetrical index detecting portion 72 calculates theleft-side integrated deceleration LV and the right-side integrateddeceleration RV. The lateral symmetrical index detecting portion 72 thendetects a ratio between the left-side integrated deceleration LV and theright-side integrated deceleration RV as the lateral symmetrical indexSY and supplies it to the type identifying portion 78. In calculatingthe lateral symmetrical index SY (0 to 1.0), the lateral symmetricalindex detecting portion 72 defines that the denominator is the largerone of the left-side integrated deceleration LV and the right-sideintegrated deceleration RV. In the case of a collision with a highsymmetrical index, namely, a head-on or pole collision, the lateralsymmetrical index SY is close to 1.0. On the contrary, in the case of acollision with a high asymmetrical index, namely, an oblique collision,the lateral symmetrical index SY is close to 0. The symmetrical indexfor ORB or ODB is between the symmetrical index for head-on collision orthe like and the symmetrical index for oblique collision. It is thusunderstood that the lateral symmetrical index SY is also an effectiveguideline for identifying a vehicle collision type.

[0122] That is, the second embodiment is designed to identify a vehiclecollision type more reliably and more easily by taking both factors,namely, an absorption state of an impact caused during a collision andthe lateral symmetrical index SY based on the integrated decelerationsLV, RV into account by using the time ratio (tn/tp).

[0123]FIG. 15 is an exemplary view of a type identifying map employed inthe type identifying portion 78 of the second embodiment. The typeidentifying map is formed of the aforementioned time ratio (tn/tp) andthe aforementioned lateral symmetrical index SY. In this typeidentifying map as well, identification areas for prediction ofrespective collision types are set. A collision type can be identifiedeasily by confirming to which one of the identification areas a pointthat is specified through determination of the time ratio (tn/tp) andthe lateral symmetrical index SY belongs. It is to be noted herein thatthe type identifying map of the second embodiment is also stored inadvance in the ROM 44 or the like in the microcomputer 40.

[0124] It is to be noted herein that the aforementioned time ratio(tn/tp) can be regarded as indicating crushability. On the contrary, thetime ratio (tp/tn) can be regarded as indicating rigidity. Accordingly,the identification of a collision type can be performed in the samemanner by using the time ratio (tp/tn) as well.

[0125]FIG. 16 shows an exemplary identification routine that is executedby the type identifying portion 78 realized by the CPU 42 of thecollision type identifying device 60.

[0126] In FIG. 16, if one of the first peak time tp and the requiredtime tn is detected, the type identifying portion 78 prepares for theidentification of a collision type (S200). Furthermore, if the remainingone of the first peak time tp and the required time tn is detected(S202), the type identification processing is performed using the typeidentifying map.

[0127] In step S204, the time ratio calculating portion 76 calculatesthe time ratio (tn/tp) from the required time tn and the first peak timetp detected. Further, in step S204, the lateral symmetrical indexdetecting portion 72 detects the lateral symmetrical index SY on thebasis of the left-side integrated deceleration LV and the right-sideintegrated deceleration RV. In step S206, a specific point determined bythe time ratio (tn/tp) and the lateral symmetrical index SY is thenlocated on the type identifying map. By subsequently confirming to whichone of the identification areas set in advance according to thecollision type the specific point belongs, a collision type isidentified (S208). The processings of the present routine are thenterminated.

[0128] A result obtained from the type identification based on thepresent routine is also used to perform activation control of thepassenger protection system 50 shown in FIG. 2.

[0129] As described above, the collision type identifying device 60 ofthe second embodiment can identify a collision of the vehicle 10 as oneof a plurality of collision types at once by using the time ratio(tn/tp) between the first peak time tp and the required time tndetermined by the floor G waveform and the lateral symmetrical index SYdetermined on the basis of the front LG and the front RG. In particular,since this embodiment is designed to perform identification inconsideration of the lateral symmetrical index determined by the frontLG and the front RG detected by the front-left and front-right sensorsas well, it is possible to identify a collision type with higherprecision. If the collision type identifying device 60 of thisembodiment is applied to a passenger protection system such as an airbag system, passengers can be protected effectively.

[0130] A collision type identifying device is disposed in a centralportion of a vehicle main body and has first deceleration detectingmeans (22), peak time detecting means (32), required time detectingmeans (34), and type identifying means (36). The deceleration detectingmeans (22) detects a vehicle deceleration in the longitudinal direction.The peak time detecting means (32) detects, as a first peak time (tp), atime from the excess of a preset threshold (GTH) by a waveform of thevehicle deceleration (G) detected by the deceleration detecting means(22) to a first peak. The required time detecting means (34) detects, asa required time (tn), a time when an integrated deceleration (VG)obtained through time quadrature of the vehicle deceleration (G) becomesequal to a predetermined integrated value set in advance. The typeidentifying means (36; 78) identifies a vehicle collision type on thebasis of the first peak time (tp) and the required time (tn). Thecollision type identifying device can identify a vehicle collision asone of a plurality of collision types at once.

[0131] While the invention has been described with reference to theexemplary embodiments thereof, it is to be understood that the inventionis not limited to the exemplary embodiments or constructions. To thecontrary, the invention is intended to cover various modifications andequivalent arrangements. In addition, while the various elements of theexemplary embodiments are shown in various combinations andconfigurations, which are exemplary, other combinations andconfigurations, including more, less or only a single element, are alsowithin the spirit and scope of the invention.

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 11. Acollision type identifying device disposed in a central portion of avehicle main body, comprising: a first deceleration detector thatdetects a vehicle deceleration in the longitudinal direction; a peaktime detector that detects, as a first peak time, a time from the excessof a preset threshold by a waveform of the vehicle deceleration detectedby the first deceleration detector to a first peak; a required timedetector that detects, as a required time, a time when an integrateddeceleration obtained through time quadrature of the vehicledeceleration becomes equal to a predetermined integrated value; and atype identifying device that identifies a vehicle collision type on thebasis of a collosion type identifying map which is formed of the firstpeak time and the required time.
 12. The collision type identifyingdevice according to claim 11, further comprising: a second decelerationdetector that is disposed in front of and to the left and right of thefirst deceleration detector and that detects vehicle decelerations inthe longitudinal direction of the vehicle as left-side and right-sidedecelerations; a time ratio calculating device that calculats a timeratio between the first peak time and the required time; and asymmetrical index detector that detects a lateral symmetrical index inthe event of a vehicle collision on the basis of the left-sidedeceleration and the right-side deceleration; wherein said typeidentifying device identifies a vehicle collision type on the basis ofthe time ratio and the lateral symmetrical index.
 13. The collision typeidentifying device according to claim 12, wherein said symmetrical indexdetector has a function of calculating a left-side integrateddeceleration and a right-side integrated deceleration through timequadrature of the left-side deceleration and the right-side decelerationrespectively and detects a lateral symmetrical index in the event of avehicle collision on the basis of the left-side integrated decelerationand the right-side integrated deceleration.
 14. The collision typeidentifying device according to claim 13, wherein said symmetrical indexdetector detects the lateral symmetrical index on the basis of a lateralratio between the left-side integrated deceleration and the right-sideintegrated deceleration, which are obtained through integration for apredetermined time set in advance after the first peak time or thethreshold has been exceeded.
 15. The collision type identifying deviceaccording to claim 12, wherein said type identifying device has acollision type identifying map which is formed of the time ratio and thelateral symmetrical index and on which a plurality of identificationareas are set, and identifies a vehicle collision type by confirming towhich one of the identification areas a specific point determined at thetime of detection of the time ratio and the lateral symmetrical indexbelongs.
 16. The collision type identifying device according to claim11, wherein said predetermined integrated value is set in advance as apredetermined integrated deceleration corresponding to a required time,which is a critical value for determining whether to activate apassenger protection system in the event of a collision of the vehicle.17. The collision type identifying device according to claim 11, whereinsaid required time detector has a function of calculating an integrateddeceleration through time quadrature of the vehicle deceleration and isso set as to start calculating the integrated deceleration upon theexcess of the threshold by the vehicle deceleration and to detect arequired time when the integrated deceleration becomes equal to thepredetermined integrated value.
 18. The collision type identifyingdevice according to claim 11, wherein said peak time detector confirmsthe first peak on the basis of an event in which a Wavelet phaseobtained by subjecting the waveform of the vehicle deceleration to aWavelet transformation processing is first inverted from 2* to 0, anddetects the first peak time.
 19. The collision type identifying deviceaccording to claim 11, wherein on said collision type identifying map aplurality of identification areas are set and said type identifyingdevice identifies a vehicle collision type by confirming to which one ofthe identification areas a specific point determined at the time ofdetection of the first peak time and the required time belongs.
 20. Thecollision type identifying device according to claim 11, wherein saidpredetermined integrated value is 0.7 to 0.8 m/s.